As you may have seen on some other thread, build with latest release of Tycho with Platform M5 product (sdk, ide...) in target-platform can result in the following error:
[ERROR] Cannot resolve target definition:
[ERROR] Software being installed: org.eclipse.platform.ide 4.8.0.I20180122-2000
[ERROR] Missing requirement: org.eclipse.platform.ide
4.8.0.I20180122-2000 requires 'config.a.jre.javase [9.0.0]' but it could
not be found
This would only affect you if you use the Platform *products* in your target-platform. It won't affect your build if it only references features or bundles directly, which are not the same way by the recent changes.
The story behind it is that in Platform M4/M5, p2 introduce a real support for BREE and that is an awesome improvement that is becoming more and more necessary with modular Java and more frequent releases.
But this major changes unveiled several pitfalls in p2 and downstream projects that were assuming that BREE support would never happen. Tycho being one of the affected components.